The present invention is an improvement made on the laser module of U.S. patent application Ser. No. 08/237,132, and now U.S. Pat. No. 5,394,430 which is an invention of the present inventor.
U.S. patent application Ser. No. 08/237,132 disclosed a structure of laser module, as shown in FIG. 5, which comprises a hollow, cylindrical casing 5 having a tapered laser beam emitting hole 51 at one end and an inner thread 52 (not shown) at an opposite end; a lens 7 mounted inside the casing 5 and retained between a cushion ring 6 and a locating ring 8; a base 9 having an outer thread 91 threaded into the inner thread 54 (not shown) on the casing 5; a laser diode chip 93 and a photo detector 94 mounted on the base 9 at right angles and respectively connected to the contact pins 92 of the base 9. The base 9 has a platform 96 to carry the photo detector 94. When the contact pins 92 of the base 9 are connected to the control circuit board (not shown), the laser diode chip 93 is controlled to emit a constant laser beam out of the tapered laser beam emitting hole 51 of the casing 5 through the lens 7. This structure of laser module is simple in structure of practical in use. However, this structure of laser module still has drawbacks. Because the contact pins 92 of the base 9 must be welded to the control circuit board, the installation procedure of the laser module is complicated. During the installation, the contact pins 92 of the base 9 will be broken easily. This complicated installation procedure greatly increases the cost of the device.